This　paper　aims　to　improve　the　working　life　of　extrusion　dies　by　optimal　structure　design,　which　plays　an　important　role　in　mass　production.　First,　an　arc-shaped　inlet　die　structure　for　an　aluminum　large-hollow-section　profile　was　developed.　Second,　a　three-dimensional　finite-element　model　of　the　porthole　extrusion　process　was　established　using　an　arbitrary　Lagrangian-Eulerian　method.　Third,　the　comparison　of　the　formability　was　analyzed　and　discussed,　including　the　diversity　of　extrusion　forces　and　uniformity　properties　between　the　proposed　design　and　two　traditional　design　schemes　using　the　same　extrusion　process.　A　group　of　square-profile　extrusion　dies　was　used　to　set　up　a　L16_4_3　orthogonal　experimental　scheme,　considering　the　side　length　of　profiles,　L,　with　four　levels,　110,　100,　90,　and　80 mm;　inlet　angles,　α,　of　the　porthole　bridge　of　0°,　10°,　20°,　and　30°;　and　profile　wall　thicknesses,　t,　of　1,　1.5,　2,　and　2.5 mm.　The　results　of　the　orthogonal　tests　were　similar　to　those　of　the　actual　production　die　model.　Two　different　analysis　models　reached　the　same　conclusion:　the　inlet　angle　or　the　arc　inlet　structure　has　a　small　effect　on　the　metal　flow　and　the　forming　distribution,　but　the　arc　inlet　structure　can　alleviate　the　stress　load　of　the　dies.　The　die　testing　and　production　validation　results　indicate　that　the　novel　structural　design　of　the　arc　inlet　die　will　have　a　long　working　life.　©　2017,　Springer-Verlag　France　SAS.